CALIBRATION OF A STELLAR INTERFEROMETER BASED ON A MULTIMODE OPTICAL-FIBER OF LOW MODAL COMPOSITION, USING A MONOCHROMATIC SOURCE

This paper discusses the possibility of using in an astronomical long- baseline interferometer a multimode optical fiber of low modal composi tion in place of the accepted single-mode fiber. To establish under la boratory conditions how contrast depends on source size and atmospheri c distortions, the visibility of the observed interference fringes was measured in a stellar Michelson interferometer. The measurements were made using a monochromatic source. By comparison with a single-mode f iber, an insignificant reduction was noted in the contrast for a multi mode fiber, along with an increase in fringe brightness.